Among the least expensive of the cameras available on the market today are miniature cameras specifically designed to take a two-lobed film cassette, one lobe containing a roll of film and the other containing a takeup spool having a film leader attached thereto. The two lobe-shaped chambers are joined by a channel member presenting the emulsion side of the film to the camera when the cassette is installed into a film-accepting chamber therein. Such films are commonly marketed in the United States under, for example, the Eastman Kodak trademark "110". Such cameras are often characterized by extreme simplicity, and are cost-engineered for the mass market. To achieve the necessary cost competitiveness, efforts are constantly being made to reduce the shutter cocking and shutter release mechanisms to the simplest, least expensive forms possible.
Probably the simplest of these is such a camera marketed by Asanuma Company of Tokyo under the trademark TOREL. The film advance and shutter release mechanism is characterized by extreme simplicity. A slider member is urged by a slider member energizing spring from a cocked, energized position to a released position. The slider member is slidably supported on a movable rail. Upon release from the energized position, the slider member is urged at high speed towards an anvil extension of an impulse-type shutter blade. The striker portion on the slider member then strikes this anvil portion in passing to flip the shutter through an exposure cycle. Film advance is secured by a rotatable thumb wheel having a gear attached thereto, the gear being disposed to extend into the dispensing chamber of the camera housing. This gear in turn is disposed to drivingly engage a similar gear provided on the takeup chamber of the cassette so as to drive the takeup spool in a film-advancing direction. Rotation of the film wheel thus advances the film.
A shutter release mechanism consists of a spring-loaded shutter release button which is coupled at one end of the slider member mounting rail to urge the rail from a dormant to a picture-taking position. The slider member has further affixed thereto a cocking member in the form of a finger-like projection configured to extend from the camera interior through the film plane, and is further disposed so that it will engage the film along a line adjoining the edge perforations thereof. In the abance of operator pressure on the shutter button, the shutter button spring urges the rod and thus the slider and the aforementioned extension into contacting engagement with the film. As the film is advanced the next frame by thumb wheel rotation, the film-engaging finger will enter a film perforation under the urging of the pushbutton spring, to be urged against the increasing form of the slider member spring to a fully energized position. Release of the slider member occurs upon depression of the shutter button causing the film-engaging member to withdraw beyond the plane of the film, whereupon the capture is lost, and the spring drives the slider member to strike the shutter.
The camera is further provided with a one-way spring-loaded pawl engaging toothed surfaces on the film wheel so that the the takeup spool can only be rotated in a film-advancing direction. Film advance termination is secured by providing another element of the slider member disposed to strikingly engage the pawl at the end of film advance, thereby forcing the pawl into a sufficiently strong engagement with the teeth of the film wheel to prevent further rotation thereof.
The above mentioned system has several disadvantages. The slider member, the film-engaging finger, and the pawl-engaging portion are all separate elements riveted together, and thus represent an expensive piece-parts manufacturing operation. Additionally, three springs are necessary, the slider energizing spring, the pawl spring, and the pushbutton return spring (in addition to the mandatory shutter return spring). A further reduction in the number of necessary parts which must be assembled to build the camera remains a desirable objective. Additionally, with no film in the camera there is no way of cocking it to make sure that the shutter release system is operating. There thus remains a need for a simple inexpensive solution to the problem of providing for some means for cocking the shutter so that the operator may test the entire system with no film in the camera. Most preferably such an auxiliary cocking system should not require the addition of a single extra part to the camera.